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Order Bunyavirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The 1.6 Å crystal structure of the RVFV hexameric ring-shaped protein N forming a functional RNA binding site and expressed in E. coli was determined (Ferron et al. 2011). This structure explained the switch from an intra- to an intermolecular interaction mode of the N-terminal arm as a general principle that underlies multimerization and RNA encapsidation by bunyaviruses. Next, the crystal structure of the protein N of an emerging phlebovirus, namely human severe fever with thrombocytopenia syndrome phlebovirus (SFTSV), was resolved (Zhou H et al. 2013). Then, the crystal structure of the RVFV glycoprotein Gc followed and demonstrated an important but unanticipated evolutionary link between bunyavirus and flavivirus envelopes (Dessau and Modis 2013; Rusu et al. 2012), namely, the gained structure was similar to that described earlier for the alphavirus E1-E2 proteins.
Rift Valley Fever
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The Phlebovirus genus is defined as being predominantly sandfly-transmitted viruses with a tripartite genome (molecular weights: L; 2.6 to 2.8 × 106; M; 1.8 to 2.2 × 106; S; 0.7 to 0.8 × 106). The type species is the sandfly fever virus, the prototype of which is the Sabin strain. The RVF virus is exceptional as the natural transmitters so far identified are species of mosquitoes.
Ticks
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
In the last decade, several new tick-borne viruses have been identified. Severe fever with thrombocytopenia syndrome (SFTS) was first described in rural areas of China, Japan, and Korea in 2011–2012. This disease, caused by a Phlebovirus, has thus far produced at least 2,500 human cases,92 and is believed to be transmitted by Haemaphysalis longicornis ticks.93 Heartland virus (a Phlebovirus) is associated with the Lone Star tick, Amblyomma americanum and has been recognized in Missouri, Oklahoma, Kentucky, and Tennessee.94,95 Only about 30 cases of heartland virus have been identified. A few cases of a new Thogotovirus called bourbon virus have been identified in the Midwest and southern United States, also with A. americanum as the vector. 9698
Candidate vaccines for human Rift Valley fever
Published in Expert Opinion on Biological Therapy, 2019
Rift Valley fever (RVF) is one of the most important zoonotic diseases in sub-Saharan Africa. Rift Valley fever virus (RVFV) belongs to the genus Phlebovirus in the family Phenuiviridae, and possesses a tripartite negative and ambi-sense RNA genome (L-, M-, and S-segments). The natural life cycle of RVFV is maintained via infected floodwater Aedes mosquitoes which lay drought-resistant eggs in low-lying areas (e.g. dambos, pans, vleis) [1]. Livestock animals susceptible to RVFV (sheep, cattle, goats, camels) play a major role in amplifying RVFV, and various mosquito species can serve as vectors for RVFV (i.e. Aedes, Anopheles, Coquillettidia, Culex, Eremapodites, Eumelanomyia, Mansonia spp.), dependent on their habitats [2]. During an inter-epidemic period, RVFV is transmitted, presumably at a low level, between mosquitoes and animals (e.g. sheep, cattle, goats, camel) in endemic countries [3]. Although viral circulation levels may not be high, RVF cases could occur in association with livestock animals or mosquitoes harboring RVFV. Once optimal conditions are met for the hatching of infected mosquitoes, higher levels of RVFV transmission can occur via mosquitoes and animals, which leads to increased cases of RVF in humans. The first described RVF outbreak occurred in Kenya in 1930–1931 [4]. Since then, there have been sporadic major RVF outbreaks affecting livestock (sheep, cattle, goats) and humans: 1950–1951 (South Africa, Kenya), 1974–1975 (South Africa, Namibia), 1977–1978 (Egypt), 1978 (Zimbabwe), 1987 (Mauritania, Senegal), 1990–1991 (Madagascar), 1997–1998 (Kenya, Tanzania, Somalia), 2000–2001 (Saudi Arabia, Yemen), 2003 (Egypt), 2006–2007 (Kenya, Tanzania, Somalia), 2007–2008 (Sudan), 2008–2009 (Madagascar). 2010–2011 (South Africa), 2010 and 2012 (Mauritania), 2016 (Niger), and 2018 (Kenya) [5–7]. In five major RVF outbreaks (1997–1998 East Africa, 2000–2001 Saudi Arabia and Yemen, 2006–2007 East Africa, 2007–2008 Sudan, 2008 Madagascar), ≈339,000 estimated human cases, 1,168 confirmed human deaths, and > 57,000 deaths of animals occurred [5,6]. RVF outbreaks mainly affected the livestock industry, due to livestock losses and trading bans of animal products [8], and thus represent an important economic and public health concerns in endemic countries.